Pointers vs functional or array semantics

[data pulverizer via Digitalmars-d-learn]

I have noticed that some numerical packages written in D use 
pointer semantics heavily (not referring to packages that link to 
C libraries). I am in the process of writing code for a numerical 
computing library and would like to know whether there times when 
addressing an array using pointers conveys performance benefits 
over using D's array or functional semantics?